Bending machine, and wire-processing system including a bending machine

ABSTRACT

A bending machine that produces complex bent parts from straight wire rods includes computer-numerical control unit; a transport system that transports successive wire rods along a transport path, wherein the transport system has a plurality of workpiece-receiving devices each for receiving a single wire rod; a plurality of workstations arranged along the transport path, wherein at least two of the workstations are configured as bending stations, wherein at least one bending station comprises a bending unit configured as a rotary draw bending unit.

TECHNICAL FIELD

This disclosure concerns a bending machine for producing complex bentparts from straight wire rods and a wire-processing system comprisingsuch a bending machine.

BACKGROUND

Bending machines typically comprise a computer-numerical control unit, atransport system for transporting successive wire rods along a transportpath, and a plurality of workstations arranged along the transport path,wherein at least two of the workstations are configured as bendingstations. The transport system has a plurality of workpiece-receivingdevices each for receiving a single wire rod. It is therefore acomputer-numerically controlled, multistation bending machine which canprocess wire rods. Such bending machines are normally used to producelarge quantities of complex bent parts in a short time. A complex bentpart is a bent part which has more than one bend, wherein the bends maypartly also lie in different planes to give a three-dimensionally bentpart.

The demand for complex bent parts exists amongst others in the sector ofelectrical mobility. There, increasingly vehicles with fully or partlyelectric drive are offered. The vehicles usually have powerful energystorage systems with multiple battery modules. The electrical energymust be transported between the individual battery modules. For this,insulated and bent copper or aluminum rails are used, also known as“busbars.” Furthermore, increasingly, the wiring looms running in thevehicle longitudinal direction between front and rear are being replacedby busbars. Since the installation space available for routing busbarsis sometimes relatively constricted and geometrically complex, in manyinstances busbars are required which have bends at one or morelocations.

Also, to produce coil elements for construction of stators for electricmotors, known as “hairpins,” often wire materials in the form ofinsulated and bent copper or aluminum wires with substantiallyrectangular or square cross-section are used.

EP 3 663 015 A1 describes a machine that produces wire elements with twolegs running substantially in a plane, with their apex lying outside theplane of the legs. The geometry is typical, e.g., for hairpins. Themachine has a supply device for substantially rectilinear wire blankswith a predefined length; a first bending device configured to perform afirst bending process on the wire blanks supplied by the supply deviceto produce flat wire elements with two legs and an apex; a plurality ofsecond bending devices which each comprise a different embossingelement, wherein the second bending devices are all configured to bendthe apex of the flat wire elements out of the plane of the legs.Furthermore, a first transport device is provided which is configured totransfer the wire elements from the first bending device to one of theplurality of second bending devices. The control device of the machineis operationally coupled to the supply device, the first bending device,the second bending devices and the first transport device forcontrolling these, and in particular is configured to actuate the firsttransport device on the basis of process parameters for transferringwire elements to a selected one of the second bending devices. Thatconcept allows amongst others a high productivity and high flexibilityin the production of bent parts with different bend geometry.

It could nonetheless be helpful to provide a bending machine of theabove type that offers a high productivity and great flexibility in theproduction of bent parts with different bend geometry, and isdistinguished by compact installation size and correspondingly littlespace requirement.

SUMMARY

We provide a bending machine that produces complex bent parts fromstraight wire rods including a computer-numerical control unit; atransport system that transports successive wire rods along a transportpath, wherein the transport system has a plurality ofworkpiece-receiving devices each for receiving a single wire rod; aplurality of workstations arranged along the transport path, wherein atleast two of the workstations are configured as bending stations,wherein at least one bending station includes a bending unit configuredas a rotary draw bending unit.

We also provide a wire-processing system that produces complex bentparts from wire including a rod make-up machine that produces straightwire rods of pre-definable length from wire material; a bending machinedownstream of the rod make-up machine that produces bent parts withcomplex bends from the straight wire rods, wherein the bending machineis a bending machine that produces complex bent parts from straight wirerods including a computer-numerical control unit; a transport systemthat transports successive wire rods along a transport path, wherein thetransport system has a plurality of workpiece-receiving devices each forreceiving a single wire rod; a plurality of workstations arranged alongthe transport path, wherein at least two of the workstations areconfigured as bending stations, wherein at least one bending stationincludes a bending unit configured as a rotary draw bending unit.

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantages and aspects arise from the appended claims and thedescription of examples which are explained below with reference tofigures.

FIG. 1 shows a schematic side view of a wire-processing system accordingto an example.

FIG. 2 shows schematically the rod-handover region and the loadingstation of the bending machine.

FIGS. 3A and 3B show in 3A a schematic view of a bending station with arotary draw bending unit, and in 3B a detail in the region of thebending head.

FIGS. 4A and 4B show schematically a possibility for rotary drawbending.

FIG. 5 shows schematically a base bending unit with horizontal bendingaxis.

FIG. 6 shows in oblique perspective the unloading station of the bendingmachine.

DETAILED DESCRIPTION

Our generic bending machine comprises at least one bending station witha bending unit configured as a rotary draw bending unit. Such a bendingunit, when fitted with a rotary draw bending tool, is able to shape thewire rod in a rotary draw bending process. A bending unit configured asa rotary draw bending unit is also described in this application as abending unit of a first type.

A rotary draw bending unit has a bending head on which, in configuredstate, i.e., with tool components for rotary draw bending attached, abending form is arranged. In a rotary draw bending operation, a portionof the wire rod to be shaped is brought into a starting position in theengagement region of the bending head. Then a clamping element of aclamping device is brought into contact with a free wire portion toclamp this wire portion against a peripheral portion of the bending formand firmly clamp it to the bending form. The wire portion is therebyfixed between the clamping element of the clamping device and thebending form. Furthermore, a counterhold device is brought intoengagement with a supply-side portion of the wire rod to stabilize theorientation of the longitudinal axis of the supply-side portion during abending operation.

Then in a bending operation (rotary draw bending operation), bysynchronous rotation of the bending form and clamping device about thebending head axis, a bend is created between the supply-side portion,stabilized against transverse forces by the counterhold device, and theclamped wire portion. The synchronous rotation of the bending form andclamping device about the bending head axis also “pulls” the workpiecearound the bending form or a peripheral portion thereof. The outercontour of the bending form may thus stabilize the inner contour of thebend and precisely predefine its radius. The rear straight leg of theworkpiece, i.e., the supply-side portion, is supported by thecounterhold device which acts a counter-bearing to absorb the transverseforces resulting from the bending, and thereby remains ideally orientedparallel to a passage direction. The passage direction corresponds tothe direction in which the wire rod is supplied in the direction of thebending form.

Ideally, a planar bend is produced in which the legs before and afterthe bend, formed by the end portion of changed orientation and thesupply-side portion of unchanged orientation, lie in a common plane. Therelative orientation of the end portion relative to the supply-sideportion is usually described as the bend angle. By rotary draw bending,the desired bend angle and bend radius can be generated with highprecision.

A preferred example of a rotary draw bending unit (bending unit of thefirst type) has a bending head which is rotatable about a bending headaxis by a bending drive, and movable parallel to the bending head axisby a feed drive. In the configured state, the bending head carries atleast one bending tool with a bending form, which is rotatable about thebending head axis by the bending drive. The rotational axis driven bythe bending drive is designated for simplicity as the Y axis. The linearaxis driven by the feed drive is designated for the sake of simplicityas the Z axis.

The Z axis is arranged transversely to the passage direction of the wirerod through the bending station and advances the bending head in thedirection of or away from the wire rod. By the rotatable bending tool,which cooperates with one or more further tool parts of the bendinghead, a planar bend can be created on the wire rod in one bendingoperation.

The preferred rotary draw bending tool (bending unit of the first type)also has, in addition to the Y axis and Z axis, a machine axis (e.g., Waxis) for actuation of a clamping device which is configured forclamping a portion of the wire rod against a peripheral portion of thebending form mounted on the bending head.

A rotary draw bending unit thus comprises at least three (regulated)machine axes.

In some examples, a rotary draw bending unit also comprises a linearaxis for displacement of the bending head parallel to a passagedirection of the wire rod (X axis, longitudinal adjustment). Thus,amongst others, in rotary draw bending, compensation movements can begenerated in the wire longitudinal direction to prevent the wire beingstretched by undesirable traction loading.

In some configurations, the rotary draw bending unit also has a linearaxis for displacement of the bending head perpendicularly to the passagedirection. This optional linear axis is here designated the B axis andallows a transverse adjustment of the bending head. Thus, in a simplefashion, bends can be generated in both directions. Also, the B axisallows use of multistage bending forms with different bend radii.

In some configurations, a rotary draw bending unit also has a rotationalaxis for rotation of a clamping device of the bending unit about thepassage axis. This optional rotational axis is here also designated theA axis and allows creation of a twist or twisted portion in the wire rodduring the rotary draw bending.

A rotary draw bending unit may thus have two or three rotational axesand two or three linear axes. More machine axes are possible but oftennot required.

In some configurations, at least one bending station has a base bendingunit with a bending head which is rotatable about a bending head axis (Yaxis) by a bending drive, and movable parallel to the bending head axis(Z axis) by a feed drive, wherein no machine axis is provided foractuation of a clamping device. Such base bending units may economicallybe provided with robust structure and, when equipped with a bendingtool, allow free-form bending in which, within constructional limits,different bend geometries can be achieved without conversion of thebending station, purely by a change of actuation. Thus, greatflexibility is achieved with respect to possible bend geometries. A basebending unit in this application is occasionally also called a bendingunit of the second type.

It is particularly favorable if the bending units are oriented relativeto one another such that the bending head axes of at least one rotarydraw bending unit and at least one base bending unit are orientedtransversely, in particular orthogonally to one another. In thisexample, bending operations which run in mutually different planes canbe divided over the different bending stations with bending units of thefirst type and second type, without the workpiece and/or a bending unithaving to be rotated over great rotational angles about the passageaxis. Any rotation about the passage axis can be restricted to smallangles of, for example, less than 45°. An orthogonal arrangement may beparticularly advantageous, e.g., for wires with square or non-square,rectangular cross-section.

Bending stations may also be provided with bending units of differentdesign. Preferably, the bending machine however comprises exclusivelyrotary draw bending units and base bending units. Thus, no great rangeof variants is required, which limits costs.

In one example, bending stations directly following one another alongthe transport path are at least partly arranged at different intervalsfrom one another. In this way, the installation space available can beutilized better than in constant intervals.

In a bending machine according to one example, the transport systemcomprises a plurality of transport units which each have aworkpiece-receiving device for receiving a single wire rod. Preferably,each transport unit is movable along the transport path by the controlunit according to an individual movement profile.

The transport units, controllable with different movement profiles, andthereby necessary supplementary measures, may be provided independentlyof the type and design of bending stations or bending units at bendingstations (also at other generic bending machines) and bring advantagesso that this aspect is also regarded as an independent disclosure.

A bending machine according to this design leaves the conventionalconcept of fixed cycling as known, for example, in revolving machines.Instead, a transport system with variable cycling is provided. The term“variable cycling” means that not all transport units are in the samemovement state at a given time, but they perform their individualtransport tasks according to an individual movement profile, wherein theindividual movement profiles of different transport units usually differat least in certain movement phases. We found that a transport systemwith variable cycling, or with the possibility of asynchronous movementof the transport units, may make a decisive contribution to achievinghigh productivity, high flexibility with respect different geometries,and small surface area requirement of the bending machines.

In an individual movement profile, starting points, end points,momentary speeds and accelerations of the individual transport units maybe variably predefined by the control unit. The movement profiles maythus differ, for example, for different path portions. The variablecycling allows, inter alia, many degrees of freedom not conventionallypresent, with respect to placing of workstations along the transportpath. For example, the intervals between successive workstations may bedifferent. This favors the reduced space requirement. The degrees offreedom with respect to the arrangement may be utilized to place theindividual workstations matched to one another, for example, withrespect to the time required for the corresponding work operations.Individual transport units (one or more) may move while others arestationary at the same time, e.g., during a bending operation. Longerbending times (duration of a bending operation at a bending station) maybe compensated at least partially with shorter transport times.

Preferably, the transport system comprises a transport path with atleast one linear motor unit and guide rails for guiding the movement ofthe transport units, wherein the transport units are movablemagnetically along the guide rails via the linear motor unit undercontrol by the control unit. The transport path may be rectilinearand/or be formed by a single linear motor unit. Preferably however,several successive linear motor units and associated guide rails areprovided. The computer-numerical control unit with operating softwareinstalled thereon allows an independent actuation of the individualtransport units with individual movement profiles. When this concept isused, a transport unit does not require its own travelling drive forprogress along the transport path. Instead, the transport unit maycomprise the passive secondary part of a linear motor with one or morepermanent magnets. The omission of dedicated drives may contribute todesigning the individual transport units relatively lightly or withlittle mass inertia so that good acceleration and high speed arepossible.

In other examples, it may be provided to integrate a dedicated drive inthe transport unit, for example, an electric motor, and create theenergy supply via the guide rails or a separate rail.

Alternatively, the transport path is a closed transport path. Thus, evenwhen many bending stations are provided, compact installation dimensionscan be maintained. With a closed transport path, returning the transportunits from an end position of their movement back to the startingposition is particularly simple. The transport path may be circular orconsist of a combination of straight portions and curved portions. Inone example, the transport path is rectangular with two long sides andtwo short sides, and with 90° curves at the corners.

Conventional fixed cycling as implemented, for example, in revolvingmachines, can in principle also be used in conjunction with bendingstations for rotary draw bending. The transport system could thus alsocomprise a revolving table on which several workpiece receivers arearranged, e.g., with fixed pitch.

Aspects of possible concepts for the workpiece receivers for transportand machining are explained below.

In many examples, components of the workpiece-receiving device incontact with the workpiece are mounted rotatably about the receivingaxis of the workpiece-receiving device. The receiving axis determinesthe orientation of the received wire rods, the longitudinal center axisof which in the region of the workpiece-receiving devices should run ascoaxially as possible to the receiving axis. Such a rotatability mayincrease the flexibility of the process guidance on bending, inparticular rotary draw bending.

In many examples, the workpiece-receiving device of a transport unitcomprises a clamping device with at least one movably mounted clampingelement and an actuating element coupled therewith, wherein by actuationof the actuating element, the clamping device can be switched between alocked configuration and an unlocked configuration. The unlockedconfiguration allows insertion of the wire rod or removal of thefinished bent part from the clamping device without mechanically loadingthe workpiece. In the locked configuration, the clamping forces exertedby the clamping device on the wire piece are sufficient to prevent theworkpiece from slipping in the clamping device during transport.

Preferably, the movable holding element is elastically preloaded intothe locked configuration by a spring arrangement. Thus, an elasticclamping is achieved which protects the workpiece. The clamping force isdetermined by the spring force of the spring arrangement which maycomprise a single spring or several springs. For insertion of the wirepiece in the clamping device, the holding element is retracted againstthe spring force; the locked configuration is assumed automatically onrelease of the holding element. The elastic clamping generally protectsthe workpiece. It is particularly advantageous when processing insulatedwire rods as used, for example, for hairpins or busbars since this typeof clamping does not load the insulation layer unnecessarily heavily.Since the clamping force is provided by the spring arrangement in thelocked configuration, the clamping device requires no external energywhich would have to be provided, for example, electrically orpneumatically.

The concept with spring-loaded holding element is a robust, fullymechanical solution with low own weight, so to this extent transportunits with lower mass inertia are possible.

Preferably, a transport unit therefore has no actuator which can beoperated with external energy, for example, a pneumatically orelectrically actuatable gripper or similar.

For correct operation of the bending of wire rods, the bending machinemust be loaded. This can take place manually. Preferably however, one ofthe workstations is a loading station for automatic or automatabletransfer of wire rods from an upstream unit for providing straight wirerods to the bending machine.

The loading station preferably comprises an actuating device,controllable via the control unit, to actuate the movable clampingelement of a transport unit. The loading station may thus switch thetransport unit between the locked configuration and the unlockedconfiguration or vice versa, so no operator intervention is required forthese steps.

Preferably, one of the workstations is an unloading station fortransferring bent parts from the bending machine to a downstream unit,wherein the unloading station preferably comprises an actuating device,controllable via the control unit, to actuate the movable clampingelement of a transport unit. The downstream unit may, e.g., be acollection container or magazine for receiving finished bent parts. Thedownstream unit may also ensure further transport of the bent parts todownstream processing devices.

Preferred examples comprise features relating to the cooperation betweenthe bending station and transport unit which conveys the wire piece tobe bent into a machining position at the bending station and later outof this again.

In some examples, a bending station is configured such that theworkpiece-receiving device of a transport unit, moved into the machiningposition, acts as a functional component of a workpiece-receiving devicefor receiving a wire rod for a bending operation. Thus, no handover ofthe wire rod between the transport unit and bending station is requiredso that faults caused by handover are systematically avoided and simplerconstruction of the bending station is possible.

Preferably, a bending station has a clamping device configured to gripon the workpiece-receiving device of a transport unit, moved into themachining position such that machining forces occurring on a bendingoperation are absorbed by the clamping device of the bending station. Inthis example, the bending station has no parts in contact with theworkpiece for fixing the wire rod. Rather, the clamping device of theworkpiece-receiving device serves as a functional part of theworkpiece-holding device at the bending station. However, no or onlyslight machining forces are transmitted to the transport unit. Thus, thetransport unit needs no specific complex construction with respect toforce loading, and the region in which the transport units cooperatewith the guide system experiences no potentially critical mechanicalload during the bending operation performed on the wire piece.

With this design, a bending station needs no dedicatedworkpiece-receiving device to receive a wire rod for a bendingoperation.

Preferably, the clamping device of the bending station is configuredsuch that a clamping force exerted on the wire rod by the clampingdevice of the workpiece-receiving device is reinforced by the clampingdevice of the bending station. This may ensure that even at highmachining forces, the wire rod cannot slip out of theworkpiece-receiving device of the transport unit during the bendingoperation.

Preferred transport units are thus used in two working states of theirworkpiece-receiving device. In one state, the workpiece is clampedmerely by spring loading, wherein the clamping force need only be sogreat as to reliably prevent the wire rod from slipping out duringtransport. In the second state, higher clamping forces occur which aresufficient to fix the wire rod reliably in the desired position duringthe bending operation.

In transport systems in which each transport unit is movable along thetransport path by the control unit according to an individual movementprofile, a particularly workpiece-protective transport can be achievedin particular for relatively sensitive workpieces such as, e.g.,relatively thin wire pieces. In some configurations, it is provided thatthe control unit is configured such that the individual movement profileof a transport unit, during movement along the transport path in itleast one compensation time interval, includes a compensation movementof the transport unit for avoiding and/or damping vibrations and/orreducing centrifugal force.

During the compensation time interval, for example, the transport unitcan thus be moved so that no vibration not previously present isgenerated in the transported wire rod. Alternatively or additionally,the movement profile may be configured such that vibration energy isextracted or diverted from an already excited vibration so thatvibration damping can be achieved. A compensation movement to reducecentrifugal force may, e.g., entail the travel speed of a transport unitbeing reduced on transition from a rectilinear portion to a curvedportion of the transport path, and/or increased on transition from acurved portion to a rectilinear portion of the transport path. Thus,curved portions can generally be traversed more slowly than straightportions. This may avoid the creation of undesired bend elements on atransported wire rod because of centrifugal forces, which elements wouldleave an undesired residual deformation on the wire rod if there were nocompensation movement. This helps ensure that the geometry of thefinished bent part corresponds to the nominal geometry within tighttolerances.

Further contributions to achieving maximum geometric precision of thefinished bent parts are made in some configurations in which theworkstations include at least one measuring station with a measuringsystem for measuring the geometry of the bent part after machining bythe bending station, wherein the control unit is configured to processmeasurement signals from the measuring system and control (subsequent)bending operations at the bending station, and/or bending operations ata downstream bending station, depending on the measurement signals.Thus, a regulated bending process can be applied which ideally allowsproduction substantially only to produce good parts, or few or norejects.

The measuring station may be physically downstream of the bendingstation and measure the bending result of the physically upstreambending station. It is also possible to integrate part of the measuringsystem of the measuring station, e.g., a camera, in the bending stationto measure the bending result. To this extent, here too, the bendingstation lies functionally upstream of the measuring station. Theworkstation could then be called a combined bending and measuringstation.

If the measurement signal is used to control the upstream bendingoperation, in some examples the machining parameters may be modified atthis bending station for machining the next supplied wire rods, to notreproduce geometry errors detected on measurement. In thisconfiguration, the measuring station is used as an after-measuringstation. Alternatively or additionally, it is also possible to use themeasuring station as a pre-measuring station in which, on significantdeviations of the geometry of the bent part from the nominal geometryfollowing the preceding bending step, the measurement signals are usedto structure the following bending operations (one or more) differentlyfrom the former parameter sets so that a detected geometry error in thebent part is at least partially corrected by subsequent bendingoperations. In this configuration, the measuring station works as apre-measuring station in which the measurement signals are used tomodify the following bending operations (one or more) with a view toreducing geometry errors.

The measurement may be performed such that the measurement object (fullyor partially bent wire rod) is at rest during measurement. Thus, maximummeasurement precision can be achieved. By a moving transport unit, themeasurement object can also be moved during measurement, wherebydifferent measurement strategies can be implemented.

Thanks to integrated testing and regulation of the geometry features(e.g., leg position or contact surface properties for hairpins ofbusbars), thus, quality control may be integrated.

We also provide a wire-processing system for producing bent parts withcomplex bends from wire. The wire-processing system comprises a rodmake-up machine for producing straight wire rods of pre-definable lengthfrom wire material, and a bending machine downstream of the rod make-upmachine for producing complex bent parts from the straight wire rods.The bending machine is designed according to our general concepts or oneof their examples.

FIG. 1 shows a schematic side view of a wire-processing system 100according to an example. The wire-processing system 100 is configured toproduce complex bent parts in the form of coil elements for stators ofelectric motors (hairpins). A starting material (also called theworkpiece) is processed which has a wire-like, electrically conductivecarrier material (e.g., copper) with substantially rectangularcross-sectional form, surrounded by an electrically non-conductiveinsulating layer of lacquer, thermoplastic or similar. The workpiece isreferred to below in brief as the “wire” D or insulated wire. Thewire-processing system is in principle also suitable for processinground material (insulated or without insulation).

The computer-numerically controlled, multiaxis wire-processing system100 has a plurality of controllable machine axes, a drive system withmultiple, usually electric drives for driving the machine axes, and acomputer-numerical control device 190 for coordinated control of workmovements of the machine axes in a production process, according to acomputer-readable control program specific to the production process.Each machine axis has at least one drive, e.g., an electric motor. Thedrive drives a movably mounted component of the machine axis. Dependingon the nature of the movement of the component to be driven (rectilinearmovement or rotary movement), one distinguishes between translationalmachine axes, here also referred to briefly as linear axes, androtational machine axes, here also referred to briefly as rotationalaxes. A linear axis may drive, e.g., a linearly movable slide. Arotational axis may drive, e.g., a turntable.

In this example, the wire-processing system has a rectangular machinecoordinate system MK characterized by lower-case letters x, y, and z,with a vertical z axis and horizontal x and y axes. In the exampleshown, the x axis runs parallel to the passage axis of the wire. Thethree regulated and driven machine axes, which are designated partly inupper-case letters (for example, A axis) at arrows, should bedifferentiated from the coordinate axes x, y and z. The arrows or doublearrows represent the work movements which can be generated via therespective machine axes or their drives. The drives are where applicablecharacterized by the corresponding capital letters of the axis and asuffix “-A” so that, e.g., the drive of the A axis is designated A-A.

The starting material D is present in the form of a wound material store(coil) which, in an example, is wound on a reel 105. In other examples,no reel is provided and the material store may also be present in andextracted from, e.g., a barrel-shaped holder.

The workpiece enters a rod make-up machine 200 with integrated strippingdevice 250. The rod make-up machine comprises, in this order along thepassage axis of the workpiece, a straightening unit 220, a lengthmeasurement device 230, the stripper device 250 equipped with a millingdevice 240, a brushing device 260 downstream thereof, an infeed device270 downstream thereof, and a cutting device 280 downstream of theinfeed device. The rod makeup machine 200 has its own base 205 on whichthe components are installed.

The straightening device 220 has two successive straightening applianceswith straightening rollers which successively machine the workpiece intwo mutually perpendicular directions, thereby straightening it. Thelength measuring device 230 has a measuring wheel and an opposingrunning wheel, and allows precise measurement of the workpiece lengthconveyed to the following units. The advance movement is generated bythe infeed device 270 which is arranged behind the stripping device 250and pulls the workpiece through the upstream devices with an infeedprofile predefinable via the controller 190, and conveys this to thedownstream cutting device 280. The advance force in the infeed direction(x direction) results from friction between the infeed rolls of theinfeed device and the wire. In other examples, a belt infeed or toothedrack infeed with reciprocally moved gripper is provided.

The cutting device 280 is directly downstream of the infeed device; nobending shaping of the flat material takes place inside the strippingunit 200 so that the cutting device separates straight wire rods DS ofpredefinable length from the partly stripped wire supplied.

These rods are transported individually and successively to a downstreambending machine 300 by a rod handover device 290. The longitudinaldirection (direction of longitudinal center axis) of the wire rods DShere runs horizontally and parallel to the transport direction of thewire rods. This may be advantageous in particular for relatively thinwires since thereby undesired deformation on accelerated movements canbe avoided. Also, this gives relatively short feed distances for thebending units, which can have a favorable effect on the processingspeed.

The bending machine 300 has its own base 305, on the top side of whichare arranged components of a transport system 310 for transportingsuccessive wire rods along the transport path 312. The transport pathruns in a horizontal plane (x-y plane). In FIG. 1 , the transport pathis shown in a schematic top view onto the transport plane forillustration in the region of the base 305.

The transport path 312 is closed in the circumferential direction andhas a substantially rectangular course with long sides running in the xdirection and short sides running in the y direction. At the cornerregions are 90° curved portions.

The transport system 310 comprises a plurality of individual transportunits 320, for example, three, four, five, six, seven, eight, nine, tenor more transport units. The number of transport units should preferablycorrespond at least to the number of workstations so that the work stepscan be carried out temporally in parallel with one another. Preferably,more transport units than workstations may be present. Each transportunit has a workpiece-receiving device 325 for receiving a single wirerod DS. In the region of the workpiece-receiving device, this runscoaxially to the receiving axis, horizontally and parallel to a passagedirection which corresponds to the local transport direction on thetransport path.

Each movement of a transport unit 320 may be carried out according to anindividual movement profile which can be predefined by the control unit190 on the basis of a computer program. The drive for the transportmovement, i.e., for the movement along the transport path 312, is hereactuated or supplied with power accordingly. The movement profile may,for example, be characterized by the distance covered on movement, thespeed and/or the acceleration of movement, all as a function of time orother parameters.

The transport units 320 are advanced by linear direct drives. Thetransport path 312 is constructed with a plurality of successive linearmotor units on which guide rails are provided for guiding the horizontalmovement of the transport units. The primary parts of the linear motorssupplied with current are situated in the transport path 312; inside thetransport unit 320 are passive components (secondary parts) of thelinear motors so that a transport unit 320 has no carrying drive foradvance movement along the transport path.

With reference to FIG. 2 , the transfer of the wire rod DS between therod make-up machine 200 and the bending machine 300 in the region of therod handover device 290 is now explained. The latter comprises ahorizontally swinging, movable gripper 292, which can each time grip astraight wire piece DS and transport it from the region of the cuttingdevice 280 to a transport unit 320 of the transport system. Theworkpiece-receiving device 325 is configured as an elastically flexibleclamping device. At least one fixedly mounted lower clamping element issituated in a holding frame 324, and opposite this an upper clampingelement 327 which is preloaded by spring force of the spring arrangement328 in the direction of the opposing fixed clamping element. Anactuating element 329 protruding outward through the holding frame, witha widened head, is arranged on the upper clamping element 327. Anunlocking device 295 which can be actuated by the control unit 190 has avertically displaceable gripper 297 which can grip the actuating elementfor transmission of tensile forces. The gripper is actuated by anelectric drive O-A and with this forms a vertical translational O axis(double arrow).

The unlocking unit 295 is part of a loading station 360 at which thestraight wire rods DS are loaded into the transport system 310. Forthis, a transport unit 320 is moved into the loading position shown. Thegripper 297 grips the actuating element and, with its assistance, pullsthe upper clamping element 327 upward against the force of the springarrangement 328 so that an unlocked configuration is reached and thewire rod DS can be inserted horizontally into the opened clamping device(workpiece-receiving device 325) without overcoming a resistance. Whenthe desired position is reached, the clamping device is transferred intoa locked configuration in which the actuating element 329 is released.The workpiece-holding device 327 holds the workpiece firmly with theforce of the spring packet 328, wherein the holding forces act over arelatively long clamping length. Then the transport unit 320 with theclamped wire rod travels along the transport path to a first workstationof the bending machine. This is a bending station 320-1 which is thefirst bending station of the transport path.

In the exemplary configuration, the bending machine 300 has threebending stations arranged successively along the transport path 312,namely a first bending station 320-1, a second bending station 320-2arranged behind this in the transport direction, and a third bendingstation 320-3 arranged behind this at a greater distance in thetransport direction. Further bending stations may be arranged along thetransport path so that, for example, four, five, six, seven or eightbending stations may be present. Bending stations may be arranged oneach side of the transport path in different positions along thetransport path. Corresponding fixing structures are prepared for this onthe machine bed. During operation, the bending stations may work inparallel, i.e., simultaneously at least in phases, whereby highthroughput rates are possible.

A bending unit is provided at each bending station, via which a bendingoperation can be performed on the wire rod. In the configuration shown,there are two different types of bending unit. At the first bendingstation 320-1 is a base bending unit 340-2 (bending unit of secondtype), with a horizontal bending head axis (see FIG. 5 ). At the secondbending station 320-2 is a rotary draw bending unit 340-1 (bending unitof the first type) with a vertically oriented bending head axis (seeFIG. 3A). At a greater distance behind this, at the third bendingstation 320-3, is another base bending unit 340-2, but with verticalbending head axis.

Each bending station is also configured to carry out geometrymeasurements on the bent part produced there. For this, FIG. 1 shows thecameras 355 of the assigned measuring systems. Thus, the bendingstations can simultaneously function as measuring stations of thebending machine. In other examples, there are separate measuringstations which are arranged downstream at a distance from a bendingstation. There are also examples without measuring system.

FIG. 3 shows a schematic view of a bending station with a rotary drawbending unit 340-1. FIGS. 4A and 4B schematically present a possibilityfor rotary draw bending. The bending unit 340-1 is configured as arotary draw bending unit. This means that by the machine axes of thisrotary draw bending unit, and a corresponding rotary draw bending tool,it is possible to shape the wire rod by rotary draw bending. In thisway, very high geometric precision can be achieved. Also, whenprocessing insulated wires as used, for example, for hairpins orbusbars, there is a relatively low risk of damaging the insulationlayer, e.g., a lacquer layer.

The rotary draw bending unit 340-1 comprises a bending head 345 whichcan be rotated bidirectionally by a electric drive (bending drive Y-A)about the bending head axis 342. The associated rotary machine axis isthe Y axis.

The bending head may be moved parallel to the bending head axis 342 by afeed drive Z-A (drive of translational Z axis). Thus, the bending headmay also be advanced by movement radially to the passage direction ofthe wire rods for bending engagement, or be brought out of engagementwith the wire rod.

In the configured state (equipped with rotary draw bending tool), thebending head 345 carries a bending form 346 which can be turned aboutthe bending head axis 342 during rotary draw bending by the Y axis.

The unit comprising the bending head is carried by a slide running onhorizontal guide rails arranged on the front side of a carrier mountedfixedly on the machine. The components carried by the slide can be movedparallel to the passage axis or transport direction (X axis) by acorresponding drive X-A.

The rotary draw bending unit 340-1 in this example has, in addition, alinear axis (B axis) which is driven via drive B-A and configured todisplace the bending head 345 horizontally, perpendicularly to thepassage direction or transport direction.

A further machine axis (W axis) is provided for actuation of a clampingdevice 347, via which a portion of the wire rod can be clamped againstthe periphery of the bending form. For the rotary draw bending, the wireis clamped between the bending form 346 and a clamping element of theclamping device 347. Then the bending form, clamping device and wireclamped in between rotate in synchrony.

In this example, the machine axis for actuating the clamping device 347is a rotational axis (W axis) which is actuated independently of the Yaxis and carries a component of the rotary draw bending tool. A relativetwist of the W axis relative to the Y axis generates a movement of aclamping element, arranged on a pivot lever, until the wire is clamped.The W axis thus controls the wire clamping. Then the bending form,clamping device and wire clamped in between rotate in synchrony.Corresponding devices for eccentric clamping are shown, for example, inEP 2 208 549 A1.

In other examples, the clamping device may also be actuated by a linearaxis which causes a linear displacement of a clamping element of theclamping device in the direction of the bending form 346 and back.

The bending station 320-1 does not have a dedicated workpiece-receivingdevice for receiving the wire piece to be bent. This is held during thebending operation by the workpiece-receiving device 325 of the transportunit 320 which is in the machining position (see FIG. 3 ). To ensurethat the wire piece does not slip during the bending operation becauseof the forces occurring inside the relatively elastically clampingworkpiece-holding device 325, the bending station has a clamping device350 with a clamping jaw 352 which is linearly displaceable via, e.g., apneumatic or electric clamping drive, and an opposite fixed clampingjaw. By the clamping device, a force can be exerted on the movingholding element 327 of the workpiece-receiving device 325, whereby thewire piece is clamped securely against extraction in theworkpiece-receiving device 325. When the clamping device 350 grips, allforces conducted via the wire onto the workpiece holding device arereceived by the clamping device so that the transport unit 320 isrelieved of bending forces and, accordingly, no specific structuralmeasures are required for high mechanical stability.

The workpiece-receiving device 325 of a transport unit 320, or thecomponents thereof touching the workpiece, are mounted rotatably about areceiving axis. During a bending operation, this runs parallel to thepassage direction. In this example, the holding elements of theworkpiece-receiving device 325 of a transport unit 320 are mounted in arotatable sleeve so that the workpiece-receiving device or its holdingelements are rotatable about the longitudinal direction of the receivedwire rod or the passage direction. The bending unit 340-1 is configuredsuch that, if necessary, it can generate a rotation of the components ofthe workpiece-holding device 325 in contact with the workpiece about thelongitudinal axis of the wire. For this, an arcuate guide 354 is mountedin the carrying structure of the bending unit, via which the clampingdevice 350 as a whole can be rotated about a rotational axis whichcoincides with the passage axis of the wire rods. The correspondingrotational machine axis is the A axis.

Thus, it is possible, inter alia, to turn the holding elements about theaxis of the held wire portion during the rotary draw bending so that onthe wire piece, not only is a bend produced but at the same time atwisted portion, i.e., a residual deformation of the wire rod whichoccurs under torsion or twisting of the wire rod.

FIGS. 4A and 4B show a variant of the rotary draw bending withsimultaneous twisting. FIG. 4A shows an axial view of the bending head345 with the bending form 346, and a clamping element 348 of theclamping device 347 which can be advanced in the direction of thebending form. FIG. 4A shows the situation before bending, wherein thewire piece DS is still straight. On the supply side, the wire piece isheld by the workpiece-receiving device 325 of the transport unit,wherein the workpiece-receiving device is clamped by the clamping device350.

A rotary draw bending operation can now proceed such that a portion ofthe wire piece is clamped at the bending form 346 and the bend isproduced by rotation of the bending form 345 such that the wire piece ispulled around the shaping contour of the bending form 346 withoutrelative slipping. The wire portion is now under tensile stress betweenthe bending head 345 and the clamping unit 350. To prevent the wirebeing stretched thereby, a compensation movement is generated by axialtravel of the bending unit via the X axis. During the bending operation,the workpiece-receiving device 325 serves as a counterhold which ensuresthat the held wire portion retains its orientation during bending. Thiscontributes to the high precision in the achievable bending angles.

Alternatively, the compensation movement may also be implemented bycontrolled movement of the transport unit in synchrony with the rotarydraw bending movements of the bending head.

In some examples of the first type, there is also a torque supportdevice 335, not illustrated in FIG. 3A but depicted schematically inFIGS. 4A and 4B, which if required can be advanced by an, e.g.,pneumatically driven linear axis, radially to the passage direction,e.g., horizontally, and in the advanced state can act clampingly on thewire the region between the bending head and the workpiece-receivingdevice of the transport unit to absorb reaction forces during bendingand where applicable during turning. The torque support device 335 maybe moved by a further, e.g., pneumatic linear axis parallel to thepassage direction, e.g., to achieve a desired distance between theclamping point at the torque support device and the bending head. Thisdistance remains constant during the rotary draw bending irrespective ofthe distance of the transport unit from the bending head. The distanceof the transport unit from the bending head arises from the distance ofthe clamping position at the workpiece-holding device 325 of thetransport unit and the current bend to be produced.

If a twisted portion is to be produced by twisting, during at least onephase of rotation of the bending head 345 by the A axis, the clampingdevice 350 is also twisted so that a twisted portion TA is producedbetween the clamped portion at the bending head 345 and the clampedportion in the workpiece-receiving device 325. In examples withengagement of the torque support device, the torque support device alsorotates during twisting via the A axis so that only the region close tothe bending form is twisted.

A base bending unit 340-2, i.e., a bending unit of the second type, maybe structurally simpler since a machine axis for actuation of a clampingdevice for wire clamping may be omitted. FIG. 5 shows schematically abase bending unit 340-2 with horizontal bending head axis 542. Arotational axis with a bending drive Y-A is provided for turning abending tool, arranged on the bending head 545 and having a bending pin547 at a radial distance from the bending head axis, about the bendinghead axis 542 and hence about the bending mandrel 546. The Z axis is amachine axis with a feed drive Z-A which can move the bending headparallel to the bending head axis. Thus, the bending head can be broughtinto and out of engagement with the wire. In this example, there is alsoan X axis for displacement of the bending unit parallel to the passagedirection, and a linear axis (B axis) for linear travel perpendicular tothe passage direction (in this example, in the vertical direction).Thus, by “pin-mandrel bending,” a flat bend can be produced in the wire.A clamping device is also provided, but has been omitted in FIG. 5 forillustrative reasons. This need not be mounted rotatably so no A axis ispresent.

Such bending units allow free-form bending in which, within structurallimits, different bend geometries can be achieved without conversion ofthe bending station, purely by changing the actuation. This achieveshigh flexibility with respect to achievable bend geometries.

In the configuration of FIG. 1 , the first bending station 320-1immediately following the rod handover device 290 has a base bendingunit with horizontal bending head axis, for example, according to FIG. 5. This is followed at a relatively close distance by a rotary drawbending unit (first type) with vertical bending head axis (see FIG. 3A),before a further bending station with a base bending unit with avertical bending head axis, for a third bending operation, follows at agreater distance. Thus, both the bending head axes of the first andsecond bending stations and also the bending head axes of the first andthird bending stations run orthogonally to one another. Thus, whereapplicable, even complex three-dimensional bend geometries withdifferent bend planes can be produced without the wire rod needing to beturned through great angles.

In the example of FIG. 1 , three successive bending operations areperformed before the finished bent part is taken from its transport unitat an unloading station 380. FIG. 6 shows in oblique perspective anunloading station 380 in which the rod is removed from the bendingmachine 300. The structure is similar to the loading station 360 insofaras a unit with M axis is provided for unlocking the workpiece-receivingdevice 325 of the transport unit 320, via which the workpiece-receivingdevice can be opened against the force of the spring packet 328. Thefinished bent wire rod, i.e., the desired bent part, is first gripped bythe gripper 692 of a rod removal device 690 which grips the finishedbent part and transports it for further processing or further machining.

To ensure a consistently high quality of the finished bent parts, ameasuring system is present at each bending station, via which geometricparameters of the bent wire rod are detected after completion of thebending operation and reported to the control unit 190 in the form ofmeasurement signals or measurement data derived therefrom. This leads toa nominal-actual comparison of the geometries and then, in greatdeviations of the measured actual geometry from the nominal geometrystored in the control unit, in this stage bending parameters of theassigned bending station can be changed so that the bend geometry can beproduced with smaller errors on the following wire piece. Themeasurement signal from the measuring station may also be used to changebending parameters at a following bending station such that any erroroccurring at a bending station can be partially or completely correctedat one or more following bending stations.

The transport system 310 with the individually controllable transportunits 320 allows the desired physical distribution of the bendingstations at varying intervals along the transport path. Thus, an overallcompact structure with relatively little space requirement can beachieved. Productivity can also be increased by the transport system310, as the total necessary transport times (secondary times) areshortened so that more time (primary time) remains for the bendingoperations. Thus, for example, after a relatively long bendingoperation, a bent part can be transported more quickly to the followingbending station than in a relatively short bending operation. Also, sometransport units can be advanced while other transport units remainstationary at their bending stations because the bending operation isnot yet complete. Finally, a transport unit can be returned very quicklybetween the unloading station 380 and the loading station 360 so thatthere is no waiting time for the productive bending operations. Incomparison with systems with fixed cycling such as, for example, arevolving transport system, variable cycling offers substantialpractical and economic advantages.

The bending stations utilize the advantages of 3D bending withoutfixed-form tools, and allow flexible changing between different hairpingeometries and also between different geometries of bent parts providedfor other applications. The bending machine is distinguished amongstothers by a high output yield with little space requirement and economicinvestment costs.

1-19. (canceled)
 20. A bending machine that produces complex bent partsfrom straight wire rods comprising: a computer-numerical control unit; atransport system that transports successive wire rods along a transportpath, wherein the transport system has a plurality ofworkpiece-receiving devices each for receiving a single wire rod; aplurality of workstations arranged along the transport path, wherein atleast two of the workstations are configured as bending stations,wherein at least one bending station comprises a bending unit configuredas a rotary draw bending unit.
 21. The bending machine as claimed inclaim 20, wherein the rotary draw bending unit has a bending headrotatable about a bending head axis by a bending drive (Y-A) and movableparallel to the bending head axis by a feed drive (Z-A), wherein therotary draw bending unit also has a machine axis (W axis) for actuationof a clamping device configured to clamp a portion of the wire rodagainst a peripheral portion of a bending form arranged on the bendinghead in the configured state.
 22. The bending machine as claimed inclaim 20, wherein the rotary draw bending unit additionally has a linearaxis (X axis) for displacement of the bending head parallel to a passagedirection of the wire rod.
 23. The bending machine as claimed in claim20, wherein the rotary draw bending unit additionally has a linear axis(B axis) for displacement of the bending head perpendicularly to thepassage direction.
 24. The bending machine as claimed in claim 20,wherein the rotary draw bending unit additionally has a rotational axis(A axis) for rotation of a clamping device of the bending unit about thepassage direction.
 25. The bending machine as claimed in claim 20,wherein at least one bending station has a base bending unit with abending head rotatable about a bending head axis by a bending drive(Y-A) and movable parallel to the bending head axis by a feed drive(Z-A), wherein no machine axis is provided for actuation of a clampingdevice configured to clamp a portion of the wire rod against aperipheral portion of a bending form arranged on the bending head. 26.The bending machine as claimed in claim 24, wherein the bending headaxes of a rotary draw bending unit and a base bending unit are orientedtransversely or orthogonally to one another.
 27. The bending machine asclaimed in claim 20, wherein bending stations directly following oneanother along the transport path are at least partly arranged atdifferent intervals from one another.
 28. The bending machine as claimedin claim 20, wherein the transport system comprises a plurality oftransport units each having a workpiece-receiving device that receives asingle wire rod, wherein each transport unit is movable along thetransport path by the control unit according to an individual movementprofile.
 29. The bending machine as claimed in claim 28, wherein thetransport system comprises a transport path with at least one linearmotor unit and guide rails that guide movement of the transport units,and that the transport units are movable magnetically along the guiderails via the linear motor unit under control by the control unit and/orthat a transport unit has no carrying drive for progress along thetransport path and/or that the transport path is a closed transportpath.
 30. The bending machine as claimed in claim 20, wherein componentsof the workpiece-receiving device in contact with the workpiece aremounted rotatably about a receiving axis of the workpiece-receivingdevice.
 31. The bending machine as claimed in claim 20, wherein theworkpiece-receiving device of a transport unit comprises a clampingdevice with at least one movably mounted clamping element and anactuating element coupled therewith, wherein by actuation of theactuating element, the clamping device can be switched between a lockedconfiguration and an unlocked configuration, and the movable holdingelement is elastically preloaded into the locked configuration by aspring arrangement.
 32. The bending machine as claimed in claim 20,wherein one of the workstations is a loading station that takes straightwire rods from an upstream unit to provide straight wire rods to thebending machine, the loading station comprises an actuating device,controllable via the control unit to actuate the movable clampingelement of a transport unit, and/or that one of the workstations is anunloading station for transferring bent parts from the bending machineto a downstream unit, and wherein the unloading station comprises anactuating device controllable via the control unit to actuate themovable clamping element of a transport unit.
 33. The bending machine asclaimed in claim 20, wherein a bending station is configured such thatthe workpiece-receiving device of a transport unit, moved into themachining position, acts as a functional component of aworkpiece-receiving device to receive a wire rod for a bendingoperation, and/or that a bending station has no workpiece-receivingdevice to receive a wire rod for a bending operation.
 34. The bendingmachine as claimed in claim 20, wherein a bending station comprises aclamping device configured to act on the workpiece-receiving device of atransport unit, moved into the machining position such that machiningforces occurring during a bending operation are received by the clampingdevice of the bending station, and the clamping device of the bendingstation reinforces a clamping force exerted on the wire rod by theclamping device of the workpiece-receiving device.
 35. The bendingmachine as claimed in claim 20, wherein the control unit is configuredsuch that individual movement profile of a transport unit during amovement along the transport path in at least one compensation timeinterval includes a compensation movement of the transport unit to avoidand/or damp vibrations and/or reduce centrifugal force, and the travelspeed of a transport unit is reduced on transition from a rectilinearportion to a curved portion of the transport path.
 36. The bendingmachine as claimed in claim 20, wherein the workstations include atleast one measuring station with a measuring system that measuresgeometry of the bent part after machining by the bending station, andthe control unit is configured to process measurement signals from themeasuring system and control subsequent bending operations at thebending station and/or bending operations at a downstream bendingstation depending on the measurement signals.
 37. A wire-processingsystem that produces complex bent parts from wire comprising: a rodmake-up machine that produces straight wire rods of pre-definable lengthfrom wire material; a bending machine downstream of the rod make-upmachine that produces bent parts with complex bends from the straightwire rods, wherein the bending machine is as claimed in claim
 20. 38.The wire-processing system as claimed in claim 37, wherein the rodmakeup machine has an infeed device that infeeds the wire from amaterial store, a straightening device that straightens the wire beforeentry into the infeed device, and a cutting device that separates thewire rod from the supplied wire, and the rod make-up machine processesinsulated wire and has an integrated stripping device that stripsportions of the insulated wire before separation of the wire rod fromthe supplied wire.